The invention relates generally to rotors for use with progressive cavity pumps or motors; more specifically, to a cast material rotor and method of forming a rotor.
Progressive cavity pumps or motors, also referred to as progressing cavity pumps or motors, typically include a power section 100, as shown in prior art FIG. 1 attached hereto, consisting of a rotor 101 having a profiled helical outer surface 103 disposed within a stator 105 having a profiled helical inner surface 107. Although stator 105 is shown with a profiled helical outer surface 111, progressive cavity apparatuses are not so limited, for example, the outer surface can be cylindrical if desired. The rotor and stator of a progressive cavity apparatus operate according to the Moineau principle, originally disclosed in U.S. Pat. No. 1,892,217. A rotor can have one less lobe than a stator.
In use as a pump, relative rotation is provided between the stator and rotor by any means known in the art, and a portion of the profiled helical outer surface of the rotor engages the profiled helical inner surface of the stator to form a sealed chamber or cavity. As the rotor turns eccentrically within the stator, the cavity progresses axially to move any fluid present in the cavity.
In use as a motor, a fluid source is provided to the cavities formed between the rotor and stator. The pressure of the fluid causes the cavity to progress and imparts a relative rotation between the stator and rotor. In this manner fluidic energy can be converted into mechanical energy.
If a progressive cavity pump or motor relies on a seal between the stator and rotor surfaces, at least one of the active surfaces can include a resilient or dimensionally forgiving material. An interference fit between the rotor and stator can be achieved if at least one of the rotor or the stator interface surfaces includes a resilient material. A resilient material can allow operation of the power section with a fluid containing solid particles as the solids can be temporarily embedded in the resilient material at the sealing interface of the active surfaces of a rotor and stator. The resilient material is frequently a layer of elastomer, which can be relatively thin or thick, disposed in the interior surface of the stator and/or on the exterior surface of a rotor. A stator or rotor with a thin elastomeric layer is generally referred to as thin wall or even wall design.
A rotor can be made of non-compliant material, for example, metal, and/or can be made of a non-compliant material body with a resilient material (e.g., elastomer) on the profiled helical outer surface of the body.